JPH0288230A - Sheet-shaped product having high strength and manufacture thereof - Google Patents

Abstract

PURPOSE: To obtain a high strength sheet-like product having an embossed decorative surface by a method wherein a surface embossing is formed in a region having a large number of bumps on one surface of a product and, at the same time, piled up films has a constitution so that no films bond with one another. CONSTITUTION: A sheet-like product 1 is made of a plurality of piled-up biaxially stretched films 5 and bonded together with one another by being compressed at an elevated temperature and has a region 2, in which a compressed and uniform polymer matrix and un-compressed regions, each of which is swollen out of a surface and which give a relief-like embossing on the surface 4. When the product is compressed with a hydraulic press at the elevated temperature, the piled films are compressed in the region 2 coinciding with the webs of a perforated plate so as to be formed into the uniform polymer matrix, while, in the regions 3 coinciding with the holes of a compression mold, no molding pressure is applied, resulting in holding the original thicknesses of the films and no film layers bond with one another in the region 3 and the film layer expands beyond the surface 4. As a result, a high-strength sheet-like product having an embossed decorative surface is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a high-strength sheet-like product of the type according to claim 1 and to a method for producing the same. Furthermore, the invention relates to the use of plastic films for producing such sheet-like products.

[Conventional technology]

Films and sheet-like products are two of the most important molded bodies in which plastics are produced as semi-finished products.

In the production of films, -axial or biaxial stretching is used industrially to improve mechanical properties (on the other hand, in the production of sheets, stretching is rarely used. The main reason for this is , the difficulties directly related to the thickness of the sheet, namely, on the one hand, the mechanical control of the stretching force in the stretching device, which increases as the thickness of the support increases, and, on the other hand, of course, to the plastic sheet of high strength. There are huge demands for this.

To solve this problem, European Patent Application Publication 0 2
07 No. 047 specification a has been published, and according to this method, a sheet with high tensile strength and high toughness is produced by thermally compressing a large number of biaxially stretched and simultaneously extruded plastic films. be done. The sheet obtained is itself homogeneous and has a smooth surface.

[Problem to be solved by the invention]

Starting from this prior art, it was an object of the present invention to provide a known high-strength sheet-like product obtained from a hot-pressed film with at least one embossed decorative surface (in this case good mechanical properties must remain intact) and the manufacturing method should be specified. Another object of the invention is to find films that are particularly suitable for this method.

[Failure to solve the problem]

This object is solved according to the invention by a sheet-like product having the features of claim '1. A sheet product is a sheet whose width and length are relatively large compared to its thickness.

Both surfaces, defined by the width and length of the sheet, extend parallel to each other and have a flat or curved, even wavy or angular shape. A number of individual ridges are present on at least one of the surfaces, these ridges forming profiled surface embossing, and the individual superimposed films are mutually VC@
Consists of uncompressed areas that do not match. However, one essential condition for mechanical strength is that this uncompressed area does not extend in all directions Pc from one end of the sheet-like product to the other end. Furthermore, the sheet may sag within this area. However, if the uncompacted area is linear or striped, its length must be significantly shorter than the width or thickness of the sheet; i.e. all of the
Desirably, the gravel-like or striped uncompacted areas extend over about 70% or less, particularly 50% or less, of the sheet spacing.

The shape of the uncompacted regions and their mutual spacing can be chosen freely by the underlying VC, as long as the strength of the sheet is not significantly reduced. In an advantageous embodiment, the uncompacted area is circular or oval or has a rectangular shape,
This bulge corresponding to one prefecture is in the shape of a spherical piece or half of a pillow that bulges out from the surface of the notebook product.

Similarly, the ratio of total uncompacted surface area to total surface area of each product is important for mechanical stability and stiffness. The proportion of the uncompacted area, that is, the area where the ridges bulge out from the sheet surface η1, is the total area of the surface of which the uncompacted area forms a part, as a percentage of the total area of each surface. It is desirable that the skin be 70% free, especially about 60% or less.

The ratio of the compressed total area to the uncompressed total area is V
In this case, ■ should not be less than the minimum value of 0.7,
In this case, each uncompressed region itself is very small, preferably less than 0.25 to 1 cm@2, and the minimum distance from one another is two rhymes. A square or circular uncompacted area should not exceed a diameter or side length greater than half the width of the product.

This is because otherwise the strength of the product would be significantly reduced.

The thickness of the sheet (depends on the intended use; this may be as long as its strength is sufficient, e.g. less than 1 layer, in particular 0.5 m).
Thicknesses up to m can be expressed. The upper limit of the thickness is determined by the manufacturing conditions V, since correspondingly thicker films must be thermally compressed. This requires, for example, a longer sniff time. However, even if the sheet has a thickness of 60 to 5 Q myx,
Furthermore, it was found that it was possible to manufacture the product.

Furthermore, this object is achieved by a method consisting of the steps according to claim 6. In this method, the biaxially oriented plastic film to be compressed, which has been provided with a heat-sealing layer on at least one side by coextrusion, is arranged in the form of a stack.

Each film is disposed on top of one another, either parallel to or on top of adjacent films, with orientation imparted by stretching. The resulting stack of films is partially, i.e. locally, compressed at elevated temperature between two press plates in a suitable embossing machine, so that at least one of the two press plates per section is compressed. The sheet is provided with an embossing die with a suitable surface pattern. This embossing compression mold has a corresponding number of depressions, depending on the desired number of ridges to be produced, and within this depression (
d During hot compression, pressure is exerted on the film stack and the film stack escapes into the area of this depression, forming a bulge.

The forming temperature is within a range above the crystalline melting point or glass transition temperature of the thermoplastic polymer forming the heat-sealing layer and below the corresponding temperature of the thermoplastic polymer forming the base layer, generally in the case of polypropylene films. C: 160 to 150°C. Once the molding temperature is reached,
The heat seal layer on the film starts to become sticky,
In contrast, the orientation achieved by the stretching of the base layer remains unchanged even at this humidity.

Preferably the pressure is at least 10 bar and in practice does not exceed 50 bar.

The duration of the molding pressure depends on the thickness of the individual films, the thickness of the stack of films2 and the thermal conductivity of the films;
and between a few seconds and 60 minutes or longer. The required number of filler films depends on the thickness of the film and the desired thickness of the sheet.

It is additionally possible to provide fine embossing, for example an increased roughness or pattern, on the surface of the sheet-like product in the area of embossing by partial compression of the film stack's proboscis.

Additionally or alternatively, complete film stacks may also be formed in oJ, resulting in sheets having, for example, a corrugated shape.

The advantage of the partial compression of the film stack according to the invention for producing compacts of good strength is that within the uncompacted area the sheet-like product bulges outwards and its improved Owing to its transparency and increased gloss, a relief-like surface area is obtained which gives a full decorative pattern on the structure. The ridges additionally have functional properties, such as improving the anti-slip properties of the surface and changing the reflectivity.

Furthermore, the aforementioned object of the invention is achieved by using an opaque film according to claim 8 when producing sheet-like products. Particularly important effects are obtained when compressing stacks of opaque films whose opacity results from filler particles or pigments. This effect is particularly impressive if the film additionally has vacuoles formed during stretching of the powder-containing base layer. When compressing such a film within a region, the vacuoles within this region are removed as a result of compression of the polymer matrix. The opacity clearly decreases within the compressed area,
And the film becomes partially IC translucent and glossy within this region. A laminated product obtained by only partial compression from an opaque film with a porous structure, according to the invention, retains the compressed matte, translucent areas and the porous structure of the superimposed film. Consists of uncompacted areas that are opaque and have a pearly luster. Furthermore, since the VC opaque region is thicker than the surrounding compressed region, a relief-like surface condition results.

A further appreciable advantage of partial compression is obtained in relation to the fracture mechanics of the final product. Regarding crack growth in homogeneous materials,
It is already known that for the duration of the damage process, e.g. the growth of an already existing cleft, in order to initiate the damage, clefts generally require a smaller force than the force required to attach the eye. . In this case, the incorporation into the product according to the invention of a whole layer in the form of an uncompacted region that stops crack formation overcomes the crack growth characteristics under the action of impact energy and impact energy and is evident ( Improved with 1,
This has proven to be a substantially effective measure, especially for reducing the overall risk of crack propagation.

Suitable materials for producing the multilayer product according to the invention are thermoplastic films oriented biaxially by stretching, ie in the machine direction 9 and in the groove direction. The film has a coextruded base layer and at least one outer covering layer of heat sealable material. In particular, it is advantageous to use films with a base layer obtained from thermoplastics from the group of polyesters and polyolefins. Polyester film usually has a ratio of 1:2.5 to 1
:6.5 in both directions, whereas polyolefin films, especially those based on polypropylene, are usually stretched and oriented in the machine direction in a ratio of 1:6 to 1:6.
and stretched and oriented in the transverse direction at a ratio of 1:8 to 1:12.

Polyesters, which emphasize certain performance properties, include polyester homopolymers and copolymers,
Mixtures 2 of various polyesters and blends of polyesters with other polymers are all to be understood.

Examples of polyesters are mono- or polycondensates of terephthalic acid, isophthalic acid and/or 2,6-naphthalene dicarboxylic acid and glycols with 2 to 101 carbon atoms, in particular polyethylene terephthalate,
These are polytetramethylene terephthalate, polybutylene terephthalate, poly-1,4-cyclohexylene dimethylene diphthalate, poly-17ethylene-2,6-naphthalene dilupoxylate, and polyethylene-P-hydroxybenzoate.

In addition, copolyester has adipic acid as a structural unit,
Sebacic acid, phthalate, isophthalic acid, 5-Na-sulfoisophthalic acid), polyfunctional trivalent components such as trimelliphic acid, etc. may be contained.

The polyester mixture may consist, for example, of at least one alkali metal salt of polyethylene terephthalate and polybutylene terephthalate, or of polyethylene terephthalate and a derivative of sulfonic acid, such as sulfoisophthalic acid.

Examples of DJ-capable or miscible polymers incorporated into polyesters include polyolefin-homopolymers or copolymers such as polyethylene, polypropylene, poly-4
- methylpentene, ethylene/vinyl acetate copolymers which can be hydrolyzed in turn - and ionomers as well as polyamides, polycarbonates, polytetrafluoroethylene, polysulfones, etc.

Suitable polyolefins for the base layer are homopolymers copolymers or terpolymers of α-olefins with 2 to 6 C atoms or mixtures thereof, in particular propylene homopolymers or ethylene and/'' or 4 to 6 C atoms! The ratio of the propylene homopolymer to the polymer mixture is preferably at least 8 DM%, especially at least 90 DM%.

The heat-sealing layer used can be a coating conventional for this purpose in film production. In the case of base layers obtained from polyolefins, this is preferably a random copolymer or terpolymer of α-olefins having a total of 2.6 and/or 4 C-atoms; In this case, preference is given to copolymers containing ethylene, terephthalate and inphthalate moieties.

If the opaque film is used for the production of sheet-like products, the base layer and optionally also the covering layer contain inert additives in the form of fine particles. The proportion of these particles is usually 1 to 25 parts by weight, especially 5 to 1 parts by weight, based on the weight of the film.
It is within the range of 5%. Average particle size is 0.05~4μ
m is particularly 0.6 to 1 μm.

Inert additives are preferably carbonates, especially carbonates of alkali gold and alkaline earth metals, such as calcium carbonate (chalk), sulphates such as barium sulphate and/or oxides such as inorganic silicon compounds, especially inorganic silicon compounds. It consists of powdered inorganic solid particles obtained from magnesium silicate (Merck), tRNa/A4, silicon dioxide and glass or titanium dioxide or its derivatives. These may be used in the form of fine particles, e.g. as a coating or pigment, in the base layer (]l-
The shape is mixed into the extruded plastic melt and dispersed therein. It is particularly advantageous to incorporate inert substances and other VU additives into the base layer in the masterbatch method.

In another embodiment, the inert additive consists of organic plastic particles that are incompatible with the polymer of the base layer and the polymer of the covering layer and have a higher melting point. These polymers include styrene and acrylic acid polymers, especially polystyrene and polymethyl methacrylate, fluorinated hydrocarbon polymers and polyamides.

In one preferred embodiment, the base layer has a porous packing. As a result, the film has a density that is lower than the density calculated purely on the basis of the used mixture of plastic and inert particles of the base layer. In particular, its density is between 0.05 and 0.859/(~3. As the degree of filth increases, the strength of the film becomes more intense, but as the number of vacuoles increases, i.e. at lower densities) ,
It is certain that a better double-possibility is obtained. The porous structure is the result of microcracks, pores, microvoids 4 or vacuoles created during stretching of the coextruded film. This stretching is carried out under temperature conditions in which the polymer matrix of the base layer cracks at the surface of the inert particles, creating free spaces, empty spaces, unfilled spaces (pores, microvoids) in the film. , vacuoles) are formed. By increasing the concentration of solid particles, the number of pores can be increased and thus the density of the film can be decreased.

The individual layers of the compression molded laminate film forming the product according to the invention are usually 10 to 300 μm, preferably 4 μm.
It has a thickness in the range of 0 to 200 μm. The thickness of the heat-sealing layer usually does not exceed 10% of the thickness of the film and is preferably between 0.5 and 5 ttm, especially between 0.5 and 2.5 μm.
It is m. The heat-seal layer is only present on one surface of the paste layer, provided that compressing the film stack between the heat-seal layer and the base layer that bounds the adjacent film produces a sufficiently firm bond. . however,
Usually films with heat-sealing layers on both surfaces are used.

The layers of the film may contain conventional additives, such as antioxidants, antistatic agents and/or stabilizers, in an effective manner.

Sheet-like products with embossed or relief-like contours on their surface can be used as decorative sheets or relief sheets, for example in the sanitary sector (walls of shower rooms).
Construction of internal decorations in the furniture industry, construction of flooring or exhibition halls, use of external decorations in the building industry, e.g. surface finishing, as well as construction of vehicles, i.e. cars, buses, railways M@
, suitable for use in the manufacture of aircraft and ships. Optionally, the external surface is provided with a fire-resistant, weather-resistant and/or chemical-resistant coating. It is also possible to incorporate suitable agents into the film, such as UV stabilizers.

Furthermore, if desired, the sheet-like product is provided with a reinforcement, preferably of metal, plastic or wood, or of cotton or non-cotton fabric, for example by lamination to a suitable jitner or film. It can also be used as a self-supporting sheet.

[Implementation]

The present invention will be explained in more detail with reference to FIGS. 1 to 6.

The sheet-like product of FIG. 1 consists of a plurality of stacked and stretched films 5 (FIG. 2).

Film 5 consists of a paste layer (not marked) and a heat seal rupture layer on both sides (not marked).

These can be reciprocated by compression at elevated temperatures.
C4 is combined. The mold used to obtain partial compression was
The simplest is a commercially available steel plate with round holes.

Depending on the chosen compression mold geometry, the product 1 is compressed to form a homogeneous polymer matrix in regions 2 and i! f, an uncompacted area 3 which clearly bulges out from the surface 4 of the product 1 as a spherical fragment and imparts a relief-like embossing on the surface 4 as shown in Figure 2;
has.

FIG. 2 represents the seed layer structure of the product 1 obtained by partial compression molding VC in a perforated, flat and smooth permanent compression mold.

The product 1 has a stack 5 of films, a flat smooth surface 6 and a surface 4 parallel thereto with ridges in the region 3. The smooth surface 6 results from placing the film stack on the press plate without interruption, whereas the embossing on surface 4 results from contact with the perforated plate. . When pressurized in a hydraulic machine at elevated temperatures, the stack of films compressed together is
It undergoes compression in the region 2 which coincides with the web of the perforated plate, forming a homogeneous polymer matrix. No molding pressure acts in the region 3, which coincides with the holes of the compression mold, so that there the film stack retains its original thickness and expands and undergoes compression 1i-i'll. This is forced to escape into the hole in the perforated plate. The parts of the film are not interconnected in the area 3 and clearly engraved from the surface 4. Although there is certainly no corresponding ridge on the opposite surface 6, this surface likewise exhibits reduced transparency and increased gloss in the corresponding area 3', so that the product (d on a smooth surface) But the decorative effect is completely off.

FIG. 6, in which the same reference numerals are used, shows the edge layer structure of the composite sheet with engravings on both sides compared to the butterfly-like implementation of FIG. Such a sheet 1 is obtained by compressing a pickled stack of film from both sides using perforated plates on each side. If the same perforated plate is placed in perfect agreement on a stack of films, the product will necessarily be a composite with the same and matching engravings on both sides. 2 electrically
By placing the perforated plates laterally opposite each other, it is possible to form offset embossments on the two surfaces of the molded article. When the entire stack of films is compressed with two completely differently embossed perforated plates, e.g. circular and square and/or plates with holes of different sizes, the product has different contoured surfaces. can also be manufactured.

It is not necessary to go into full detail within the scope of the invention that other desired surface engravings can be obtained by selecting a suitable compression mold, for example a male instead of a female mold.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing one embodiment of the sheet-like product according to the present invention, and FIG. 2 shows the embodiment of FIG.
FIG. 6 is a cross-sectional view showing a more detailed enlarged view along a line, and FIG. 6 is a cross-sectional view showing another embodiment. 1... Product, 2... Compressed area, 3... Uncompressed area, 3'... Area where the ridge corresponding to 3 is not completely formed, 4... Surface, 5... Film a pile of
6...Flat and smooth surface. 7 - Input... Product... Area that has been compressed... Area that has not been compressed... Area that does not have a raised part corresponding to 6.・・・
・・Surface・・・・Film σ) Loading truck cat・・・Smooth surface with Y et al. [

Claims (1)

[Claims] 1. A high-strength sheet-like product consisting of a plurality of superimposed films of thermoplastic material rigidly bonded to each other, wherein at least one surface of the product has a large number of individual ridges. of high strength, characterized in that the product has a greater thickness in the area of the ridges of this surface and the individual films are not bonded to each other in the area of the ridges. Sheet products. 2. A claim in which both surfaces are embossed and consist of partially compressed, preferably precisely coincident regions, with the ridges of the uncompacted regions being present on both surfaces of the product. The sheet-like product described in item 1. 3. The proportion of uncompacted area on each surface of the sheet product is 7 for these surfaces of the sheet product.
Sheet-like product according to claim 1 or 2, wherein the sheet-like product does not exceed a value of 0%, in particular 60%. 4. A sheet-like product according to any one of claims 1 to 6, comprising a compressed opaque film. 5. The base layer of the thermoplastic film consists of a material selected from the group of polyesters, in particular polyethylene terephthalate, in particular polyolefins with propylene units, polystyrene, polyamides, polyvinyl acetate, or copolymers or mixtures thereof; In particular, this film preferably has a thickness of 10 to 300 micrometers,
5. Sheet-like product according to claim 1, having a thickness of from 40 to 200 micrometers. 6. A method for producing a sheet-like product according to any one of claims 1 to 5 by compressing a stack of thermoplastic films at elevated temperatures, in which at least one compression mold has a plurality of indentations. a stack of film is placed between two compression molds having a recessed area in which no pressure or only reduced pressure acts on the respective surface of the stack of film during compression. The method for producing a sheet-like product according to any one of claims 1 to 5. 7. The stack of films is placed between two compression molds having recesses, the embossing of the two compression molds being coincident or laterally staggered. the method of. 8. Sheet-like product according to claim 6 or 7, comprising a thermoplastic film consisting of a base layer containing particles of an inert substance and at least one heat-sealable surface layer and having a porous structure. manufacturing method.